Network Virtualisation (NV) is a process in which logical representation of underlying physical networks is created. Such a logical (or virtual) network is decoupled from hardware and software of the underlying physical network resources. By creating virtual network(s) it is possible to simulate the hardware network resources by running specialised software on general hardware. For example, a switch or a router can be simulated on a general purpose computer that is equipped with ports for connecting physical links. All the functionality of the device is separated from the hardware and simulated as a “virtual instance”. In such a virtual switch or router the hardware part is responsible for receiving packets and forwarding these packets towards their destination, but it is the software in the virtual network of a number of these switches or routers that allows for deploying and management of services and underlying network resources. Thanks to the centralization of control functions and separation from data-plane, SDN is a valuable enabler for network virtualisation.
Network Virtualisation (NV) is a very promising trend of enabling effective managing of data-centers. In this context the transport network assumes a new role of providing dynamically E2E (end-to-end) connectivity. One of the main aspects of NV is the ability to create a smart logical and abstract view of the physical network resources (like packet and optical switches, routers, etc.) that allows for hiding hardware complexity and constrains.
With the advent of datacenter services the transport network is likely to become more flexible and more programmable and software-driven. The network virtualisation of functions pushes for organization of the functions in a cloud environment and the distribution of the data-centers in the network. In such context the connections among such datacenters (located in WAN—Wide Area Network) must be virtualised and represented in an abstract way in order to simplify handling of datacenter service according to the paradigm of Infrastructure as a Service (IaaS).
Network Virtualisation (NV) is considered a key mechanism to decouple network from service. With the term Network Virtualisation referred herein associated is the ability to create a smart logical and abstract view of the physical network resources that allow for deployment and management of services and use of the underlying network resources.